Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

DNA topology in histone- and protamine-depleted nuclei (nucleoids) from somatic cells, sperm, and spermatogenic cells was studied to determine if the superhelical configuration of DNA looped domains is altered during spermatogenesis. The expansion and contraction of nucleoid DNA was measured with a fluorescence microscope following exposure of nucleoids to different concentrations of ethidium bromide (EB). Nucleoids from Xenopus laevis erythrocytes, primary spermatocytes, and round spermatids, and from Rana catesbeiana sperm all exhibited a biphasic change (condensed-relaxed-condensed) in size as a function of exposure to increasing concentrations (0.5-100 micrograms/ml) of EB, indicating that they contain negatively supercoiled DNA. In contrast, DNA in sperm nucleoids from Xenopus laevis and Bufo fowleri was relaxed and expanded at low (0.5-6 micrograms/ml) EB concentrations, but became gradually condensed as the EB concentration was increased (6-100 micrograms/ml). Nucleoids prepared from all cell types retained the general shape of the nucleus regardless of the superhelical configuration of the nucleoid DNA. Sperm nucleoid DNA condensed by 100 micrograms/ml EB was relaxed by exposure to UV light, DNase I, proteinase K, or 4 M urea, but not by RNase A or 10 mM dithiothreitol. These results demonstrate that the DNA in sperm nucleoids is constrained in domains of supercoiling by nonbasic nuclear proteins. Negatively supercoiled DNA is present in nucleoids from cells with a full complement of histones, including Rana sperm, but not in nucleoids from Xenopus and Bufo sperm in which histones are replaced by "intermediate-type" protamines. Histone replacement in these species, therefore, is accompanied by unfolding of nucleosomal DNA and active removal of the negative supercoils. Results presented also suggest an important role for the nonbasic nuclear proteins of sperm in the morphogenesis of the nucleus and the arrangement of DNA.
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PMID:Changes in DNA topology during spermatogenesis. 349 Mar 60

An intracellular effect of nickel(II) which may be involved in its carcinogenic action is the alteration of normal DNA-protein binding. This effect of ionic nickel was studied in Chinese hamster ovary cells using several chromatin isolation methods in combination with SDS-polyacrylamide gel electrophoresis. DNA from cells incubated with (35S)-methionine or (35S)-cysteine to radiolabel protein was prepared by three methods: (solation of nuclei or nucleoids followed by chloroform-isoamyl alcohol (24:1 v/v) extraction and in some cases an additional extraction in the absence or presence of 2M NaCl, 40 mM EDTA or SDS; by isopycnic centrifugation through Cs2SO4 gradients containing 0.8% sarkosyl, 2.2 MCs2SO4, 1 mM NaCl and 10 mM EDTA; or by chromatin disaggregation and denaturation using 9 M urea, 2% 2-mercaptoethanol, 4% Nonidet P-40 +/- 2 M NaCl. DNA from nickel-treated cells consistently had more (35S)-methionine radioactivity associated with it than did DNA from untreated cells. This radioactivity was resistant to ribonuclease but sensitive to protease. Differential extraction using denaturing agents and high ionic strength followed by SDS-polyacrylamide gel electrophoresis revealed that most of the tightly bound proteins were nonhistone chromosomal proteins, and possibly histone 1. The enhancement of DNA-protein binding from nickel-treated cells was disrupted by SDS, suggesting that nickel ions do not function as classical bifunctional crosslinking agents. Since regulation of DNA replication and gene expression is dependent upon DNA-protein interactions, the effect of nickel in altering the extent of DNA-protein binding may interfere with this regulation and may contribute to the carcinogenic activity of nickel compounds.
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PMID:Effects of nickel(II) on nuclear protein binding to DNA in intact mammalian cells. 362 Nov 37

In our search for potential folding intermediates we have prepared and characterized the fragment of RNase A corresponding to residues 50-61. Proton chemical shift variations with temperature, addition of stabilizing (TFE) or denaturing agents (urea) provide a strong experimental basis for concluding that in aqueous solution this RNase fragment forms an alpha-helix structure similar to that in the intact RNase A crystal. This conclusion lends strong support to the idea that elements of secondary structure (mainly alpha-helices) can be formed in the absence of tertiary interactions and act as nucleation centers in the protein folding process.
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PMID:1H NMR and CD evidence of the folding of the isolated ribonuclease 50-61 fragment. 362 71

We have identified a pentapeptide region of microinjected ribonuclease A that is required for enhanced degradation of this protein during serum withdrawal. We introduced reductively methylated [3H]ribonuclease A, [3H]ribonuclease S-protein (residues 21-124), and [3H]ribonuclease S-peptide (residues 1-20) into the cytosol of human fibroblasts by red cell-mediated microinjection and osmotic lysis of pinosomes. The degradative rates of ribonuclease A and ribonuclease S-peptide are increased 2-fold upon withdrawal of serum, while catabolism of ribonuclease S-protein is not regulated in this manner. Certain fragments of ribonuclease S-peptide are also degraded in a serum-dependent fashion (residues 1-14 and 4-13), while other fragments are not (residues 1-10 and 2-8). [3H]Ribonuclease S-peptide is cleaved into two smaller radioactive peptides during loading into red cell ghosts. We tentatively identified the larger fragment as residues 7-11 based on its molecular weight determined by Sephadex chromatography in the presence of 8 M urea combined with sequential Edman degradation to identify the position of radioactive lysines. The smaller peptide fragment appears to be the amino-terminal dipeptide, Lys-Glu, and/or residues 7-8, Lys-Phe. After microinjection into fibroblasts, the pentapeptide is degraded at an enhanced rate in the absence of serum, while degradation of the dipeptide is not affected. We confirmed that residues 7-11 constitute the larger hydrolysis product of S-peptide by synthesizing this pentapeptide and radiolabeling it by reductive methylation. It migrated at the expected position after Sephadex chromatography in 8 M urea and was further hydrolyzed only slightly during loading into red cells. Finally, degradation of this pentapeptide after injection into fibroblasts was enhanced 2-fold upon serum withdrawal. These results, combined with our other recent studies (McElligott, M. A., Miao, P., and Dice, J. F. (1985) J. Biol. Chem. 260, 11986-11993), suggest that the pentapeptide, Lys-Phe-Glu-Arg-Gln, targets microinjected ribonuclease A to lysosomes for enhanced degradation during serum deprivation.
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PMID:Regulation of catabolism of microinjected ribonuclease A. Identification of residues 7-11 as the essential pentapeptide. 370 Apr 19

A specific high-affinity folate binding protein (FBP) that binds folic acid and folic acid derivatives and that was previously identified in porcine kidney has been purified 50,000-fold using the technique of affinity chromatography. The FBP had a molecular weight of 38,500 daltons and did not appear to aggregate in solution, as has been reported to be the case with folate binding protein from milk. At pH 7.6, the Ka was at least 5 X 10(12)M-1. At pH values greater than 9.5 or less than 5, the binding dramatically decreased. The specificity was determined by an isotopic dilution technique using [3H]folic acid and folic acid analogs and derivatives. The FBP reacted more rapidly with unsubstituted folates, and the number of glutamic acid moieties (N greater than or equal to 1) did not influence binding. Binding of folic acid to the FBP was unaffected by a variety of anions and cations, and 8 M urea, but was disrupted by 6 M guanidine hydrochloride. Proteolytic enzymes irreversibly destroyed binding affinity, but RNase, DNase, phospholipase and neuraminidase had no effect.
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PMID:Properties of a folate binding protein (FBP) isolated from porcine kidney. 372 88

To determine whether tubular reabsorption of low molecular weight proteins (LMWPs) alters ischemic tubular injury, rats were infused with 25 mg of lysozyme (isoelectric point (pI) 11.3), cytochrome C (pI 10.6), ribonuclease (pI 8.7), or myoglobin (pI 7.0), and during this time 25 minutes of bilateral renal artery occlusion (RAO) was induced. RAO control rats received either saline or 25 mg of albumin. Renal injury was assessed 24 hours later by blood urea nitrogen, creatinine, and histology. Lysozyme, ribonuclease, and myoglobin each exacerbated ischemic damage (increased tubular necrosis, cast formation, azotemia), but to comparable degrees (e.g., blood urea nitrogen range 75 +/- 8 to 100 +/- 5 mg/dl versus controls, 29 +/- 2 to 36 +/- 7; p less than 0.01). Rendering lysozyme anionic (pI 4.5) by succinylation did not diminish its acute renal failure-potentiating effect. Cytochrome C which is freely filtered but poorly reabsorbed had a minimal impact on the ischemic process. Infusion of LMWPs did not alter blood pressure, renal blood flow, or induce renal injury in the absence of RAO. During a sublethal ischemic event (10 minutes of RAO) LMWP infusion exacerbated proximal tubular luminal membrane damage before an adverse effect on other critical determinants of cell integrity were apparent (adenine nucleotide pools, oxidant stress). We conclude that endocytic LMWP reabsorption by proximal tubules can exacerbate superimposed ischemic tubular necrosis independent of any direct nephrotoxic protein effect. This action is not influenced by protein isoelectric point and appears to be mediated by a primary intensification of ischemic luminal membrane damage.
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PMID:Low molecular weight proteinuria exacerbates experimental ischemic renal injury. 380 17

The intimate structure of the complexes located at the sites of DNA loops attachment to the nuclear skeleton was analysed. It is shown that: there are at least three components of the attachment site complex: DNA, protein, RNA; protein moiety consists of 7-8 species with Mr 70-17 kDa. Their association with DNA is resistant to ionic detergents, high salt and urea treatments. The DNA-protein complex is also resistant to the SDS-pronase-phenol deproteinisation procedure; the buoyant density of the complex is the same as DNA density. RNase digestion at low ionic strength reduces density of the complex while the same treatment at 0,4 M NaCl has no effect; DNA-protein complexes isolated with urea-high salt treatment are visualised as globular particles 25-35 nm in diameter with DNA loops attached. These particles were not observed after detergent treatment although protein composition of the complex remained the same.
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PMID:[Composition, structure and various properties of DNA-protein complexes located at the sites of DNA loop attachment to the nuclear skeleton]. 380 12

The refolding of urea-denatured ribonuclease A was measured at 0.31-3.1 mol . l-1 urea in the presence of various concentrations of peptidyl-prolyl cis-trans isomerase isolated from pig kidney. The rate of the slow CT-phase in the refolding reaction was found to be sensitive to this enzyme. A rate enhancement proportional to the isomerase activity has been observed. The activity of the enzyme was assayed with Glt-Ala-Ala-Pro-Phe-4-nitroanilide. The catalytic activity of the isomerase against unfolded ribonuclease is suppressed after preincubation of the enzyme with 0.001 mol . l-1 Cu2+, 0.01 mol . l-1 H+ and by heat inactivation. The results indicate the involvement of the cis/trans interconversion of proline peptide bonds during the refolding of ribonuclease A.
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PMID:The refolding of urea-denatured ribonuclease A is catalyzed by peptidyl-prolyl cis-trans isomerase. 388 50

Sterile, concentrated culture supernatant from Pasteurella haemolytica (biotype A, serotype 1) strain 630 was subjected to physical, chemical, and immunologic treatments to determine their influence on leukotoxin (cytotoxin) activity contained in the supernatant. Each treated sample contained approximately 8 chemiluminescence inhibitory units of leukotoxin. Treatment effects were evaluated for their ability to inactivate leukotoxin activity. Leukotoxin activity in treated samples was determined by inhibition of the luminol-dependent chemiluminescence response of bovine neutrophils. Optimal leukotoxin synthesis by P haemolytica occurred when the bacteria were at the logarithmic growth phase, whereas stationary phase cultures contained minimal amounts of leukotoxin activity in their culture supernatant. Leukotoxin activity was heat labile; activity was substantially decreased when concentrated culture supernatant samples containing leukotoxin activity were incubated at 37 C for several hours. When concentrated culture supernatant was incubated at progressively decreasing temperatures, there was a progressive increase in the length of time that the leukotoxin retained its biologic activity. Samples stored at -70 C retained activity for at least 2 months. Leukotoxin activity was nondialyzable and was able to withstand considerable extremes in hydrogen ion concentration. Leukotoxin activity could not be pelleted when subjected to forces of 100,000 X g for 1 hour. Chemical and enzymatic studies suggested that P haemolytica leukotoxin contained carbohydrate and protein moieties. Chemical treatment with 0.2% sodium lauryl sulfate, 0.5% sodium deoxycholate, 7.5 mM EDTA and 8M urea with 8 mM 2-mercaptoethanol and enzymatic treatment with lipase, ribonuclease, and deoxyribonuclease had no discernible effect on leukotoxin activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Pasteurella haemolytica leukotoxin: physicochemical characteristics and susceptibility of leukotoxin to enzymatic treatment. 396 75

A new method to determine oligo- and poly(ADP-ribosyl)ated enzymes and proteins in vitro has been developed. This method is based on the facts that in Mg2+-depleted condition automodification of poly(ADP-ribose)polymerase is minimized and exogenously added acceptor protein is oligo(ADP-ribosyl)ated predominantly, and in Mg2+-fortified conditions the exogenous acceptor can be poly(ADP-ribosyl)ated. When 13 proteins, including several enzymes, were subjected to this system, dimeric bovine seminal RNase and micrococcal nuclease were found to be oligo(ADP-ribosyl)ated under Mg2+-depleted conditions but their activity was unchanged. Under Mg2+-fortified conditions however, the RNase was deactivated concomitantly with its extensive poly(ADP-ribosyl)ation. When dimeric bovine seminal RNase was monomerized in advance by treatment with dithiothreitol and urea, the enzyme lost ADP-ribose-accepting ability in spite of a significant residual enzyme activity. As used here successfully, the Mg2+-depleted and Mg2+-fortified ADP-ribosylation and subsequent chromatographic analysis of various proteins and enzymes might be an useful method for proving their oligo- and poly(ADP-ribosyl)ation.
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PMID:A method for determining oligo- and poly(ADP-ribosyl)ated enzymes and proteins in vitro. 400 56


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